Method of oil fog lubrication



W. L. SHIVELY METHOD OF OIL FOG LUBRICATION March 5, 1935.

Filed 'Jan. ll, 1950 amcas IN VEN TOR. Via/78f Z. Jfi/Z Gy B Y TT NE Y.

Patented Mar. 5, 1935 PATENT OFFICE METHOD OF OIL FOG LUBRICATION WalterL. Shively, Wilkinsburg, Pa., assignor to The Koppers Company ofDelaware, a corporation of Delaware Application January 11 4 Claims.

This invention relates to the injection of oil vapor into gas mains forthe creation of oil fog within the gas streams therein. In particularthe invention is applicable to mains such as are used for thedistribution of city gas.

In conjunction with the distribution of dry gas, the admixture of an oilfog or mist with the gas has been found desirable. The purpose of theoil fog is to create an oil moist condition for the interior of thedistribution system to replace the water moist condition existing priorto the Y use of dry gas. Such an oil coating prevents dust troubles,seals minute leaks in the main and joints, prevents the drying out ofjointpacking,

further reduces corrosion, alleviates naphthalene troubles, and has abeneficial efiect on meter leathers.

An oil fog is not so essential in a stream of dry gas that is passedthrough new mains or pipes as it is when the dry gas is passed through asystem of pipes previously containing moist gas. The moisture will havebrought about accumulations of rust and saturated pipe joint packings.The subsequent passing of dry gas converts the rust accumulations intodust and desiccates the packings until they leak gas.

Existing methods for the formation of a suitable fog'consist ofatomization of .the oil with compressed gas or the oil saturation of aportion of a gas stream with recombination of the hot saturated gas withthe main stream to produce the necessary chilling and condensation ofthe oil. These methods require a supply of gas at higher pressures thanthe main body of gas with which the fog is to be mixed.

Since oil fog equipment must often be installed in places where thepower sources for the equipment to provide the gas pressure are notavailable or where the operation of such devices might constitute anexplosion hazard, the requirement of higher pressure gas for existingmeans constitutes in many cases an objection to their use. It is thepurpose of this invention to overcome the necemity for gas at a pressurehigher than that of the gasin the system which it is proposed tolubricate.

The underlying principle of this invention is the vaporization of asuitable oil and the introduction of quantities of the vapor in the gassubstantially in excess of that required to saturate the gas. Thepressure created by such vaporization furnishes the pressure required toforce the vapor into the gas stream. A further novelfeature of thisinvention is the creation of the fog in the main body of gas itselfrather than 1930,. Serial No. 420,135

externally as previously done. In the drawing, Figure 1 is a verticalsection of apparatus that vaporizes the oil under slight pressure;

Fig. 2 is a vertical section of apparatus that vaporizes the oil underconsiderable pressure;

Fig. 3 is a vertical section of apparatus that vaporizes and superheatsthe oil; and

Fig. 4 is an enlarged cross-sectional detail of parts shown in Fig. 2.

In each of the views a boiler 1 supplies oil val0 por through a pipe 2to a gas main 3. The oil vapor is dispersed in a stream of gas in pipe 3by means of a nozzle 4.

Oil is supplied to the boiler 1 through a feed pipe 5 and is vaporizedby means of a gas burner 15 6 supplied with gas through a pipe 7. Thesource of the gas for pipe '7 may be the gas main 3.

The boiler 1 and burner 6 are surrounded by a jacket 9 and the productsof combustion are conducted to the outside air through a stack 10. 20Air is admitted to thebottom of jacket 9 through an inlet pipe 11. Theburner 6 is kept from communication with its immediate surroundingsbecause the burner and boiler 1 are located in a gas governor pit wherethere is a possibility of 25 accumulations of gas from leaks.

The embodiment of the invention, shown in, Fig. 1, vaporizes the oil ata pressure that is merely suflicient to overcome the pressure of the gasin the gas main 3.

The modification shown in Fig. 2 is provided with a nozzle 4 having arelatively small constrlction and the oil vapor pressure in boiler 1 maybe from 5 pounds to 100 pounds per square inch. The boiler shown in Fig.2 is provided with a pressure responsive diaphragm 12, shown enlarged inFig. 4, which is connected to a hydrostatlc bellows 13 that in turnregulates the amount of gas passing through pipe '7 to burner 6. Theboiler 1 is provided with a safety valve 14, a pressure gauge 15 and apipe 16 for conducting any oil vapor liberated by the safety valve 14 tothe atmosphere.

The modification shown in Fig. 3 difiers from the embodiment shown inFig. l in having an ex- 4 tension of the pipe 2 formed into asuperheating coil 17 that is located in the flame above the burner 6.After the oil vapor'leavesthe boiler l and passes through thesuperheater 17 it conr tinues through pipe 2 past a bulb 18 filled withvolatile fluid. The pressure from the bulb 18 is communicated to ametallic bellows 19 which diminishes the flow of gas through pipe 7 asthe temperature of the oil vapor leaving superheater 17 becomes higher.

The rate of boiling is such that quantities of oil substantially inexcess of those required to saturate the gas are used. As an example,the use of from 2 to 5 gallons of gas oil per million cubic feet of gaswould be contemplated with an oil of which one gallon could be carriedby the gas in the vapor phase at the temperature prevailing in thedistribution system. The excess of oil vapor over that required tosaturate the gas must necessarily condense at ordinary gas maintemperatures forming a fog or mist. I As the oil vapor is dispersedthrough the stream of gas in the main 3 by means of the nozzle 4 asudden chilling of the oil vapor occurs in the ensuing eddy currents.This suddenness of chilling prevents the formation of large particleswhen the oil changes from vapor to liquid that would later settlereadily. Since more than enough of the oil to saturate the gas issupplied the fog is quite persistent. It is removed by impingementagainst surfaces rather than by gravitational settling.

The oil preferably is a petroleum distillate having characteristicssimilar to those of absorbent or wash oils used in light-oil recoveryplants. The specific gravity should range from 0.86 to 0.89 at 60 F. andthe distillation range first drop 590 F. (310 C.), ml.'distilled at 650F. (343 C.), 90 ml. distilled at 650- F. (388 0.), end point 750 F. (3990.). The sulfur content should not exceed 0.5 per cent by weight and thecarbon residue or coke should not exceed 0.05 per cent by weight. Thepour point is not important and no limit is set. The viscosity willusually range from 160 seconds to 425 secondsSaybolt at'50" F. and theoil should be free of water. The oleflne content is not often importantprovided the oil vaporized in the gas does not form or promote theformation of gummy deposits in the transmission system, but the oleflnecontent will usually be less than 20% by volume; and the oil shall bepresence of rust, is eliminated, pipe joint pack-' ings are kept fromshrinking, and the benefit to the leather of meter bellows are a few ofthe advantages.

The advantages of the present method, that employs heat, over othermethods is that no source of power for compressing gas is necessary,

at the point where oil fog is formed and such places are usuallyisolated and remote from the main gas plant.

Moreover there are no working parts to require frequent adjustment. Thefuel for heating the oil is always available from the same gas-- maininto which the oil fog is to be dispersed although electric heaters orany other type of heater may be used without departing from the scope ofthe invention as herein claimed.

I claim as my invention:

1. A method of lubricating a gas main distribution system by producingoil fog in a stream of gas comprising heating oil in an enclosed zoneoutside said system to vaporize the same and generate by vaporizationgas pressure substantially just in excess of that of the gas in the gasmain system, introducing the so vaporized oil vapor into the gas mainsystem during the fiow of the stream of gas therethrough under the gaspressure generated bythe vaporization of the 011 against the gaspressure in the system and in amounts in excess of that required tosaturate the gas to commingle with the stream of gas, condensing the oilvapor in the gas in the gas main system itself so as to form an oil fogthat is carried along the system as an oil mist, and thereby lubricatingthe gas main system.

2. A method of lubricating a gas main distribution system by producingoil fog in a stream of relatively cool gas comprising: heating oil in anenclosed zone outside the system to produce condensible vapor from theoil and generate pressure; introducing the vaporized oil into the gasmain distribution system from the heating step during fiow of the streamof gas at lower temperature in the distribution system, and against thepressure of the gas in the distribution system under the pressurecreated by the vaporization of the oil in the heating step, and in anamount in excess of that required to saturate the gas, and comminglingthe hot oil vapor with the stream of gas; and condensing the excess oilvapor in the gas main systemto form a highly persistent oil fog misttherein.

3. A method of lubricating a gas main distribution system bydistributing oil in a stream of relatively cool gas in the gas mainsystem in the form of finely divided particles constituting a fog, saidmethod comprising heating a body of said oil in an enclosed zone outsidesaid system to vaporize the oil and generate therewith gas pressure,superheating the vapor to produce a condensible superheated vapor, thenconducting the superheated vapor under the gas pressure generated by theheating of the oil into the gas main system during flow of relativelycool gas therethrough, and condensing the superheated vapor into fogtherein.

4. A method of lubricating a gas main distribution system bydistributing oil in a stream of relatively cool gas in the gas mainsystem in the form of finely divided particles constituting a fog, saidmethod comprising, heating oil in an enclosed zone outside said systemto vaporize the oil and generate therewith gas pressure greater thanthat of the gasin the system, then conducting a stream of the so heatedhot oil vapor into the gas main system during fiow of relatively coolgas there- WALTER L. e s.

